U.S. patent application number 10/552041 was filed with the patent office on 2006-11-30 for heat exchanger.
This patent application is currently assigned to BEHR GmbH & CO. KG. Invention is credited to Uwe Forster, Kurt Molt.
Application Number | 20060266509 10/552041 |
Document ID | / |
Family ID | 32981038 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060266509 |
Kind Code |
A1 |
Forster; Uwe ; et
al. |
November 30, 2006 |
Heat exchanger
Abstract
The invention relates to a heat exchanger, especially a gas
cooler for C02, embodied as a cooling agent. The heat exchanger
comprises at least one two-part collector unit made of a base and a
cover. Said collector unit consists of flat pipes and at least two
longitudinal channels with an essentially circular cross-section.
The ends of the flat pipes and the base comprise openings for
receiving the ends of the pipes. The base, cover and flat pipes are
soldered together.
Inventors: |
Forster; Uwe; (Ludwigsburg,
DE) ; Molt; Kurt; (Bietigheim-Bissingen, DE) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
BEHR GmbH & CO. KG
Mauserstrasse 3
Stuttgart
DE
70469
|
Family ID: |
32981038 |
Appl. No.: |
10/552041 |
Filed: |
March 22, 2004 |
PCT Filed: |
March 22, 2004 |
PCT NO: |
PCT/EP04/03016 |
371 Date: |
October 3, 2005 |
Current U.S.
Class: |
165/173 ;
165/110 |
Current CPC
Class: |
F28D 1/05366 20130101;
F28F 9/0214 20130101; F28F 9/0224 20130101; F28F 2275/04 20130101;
F28D 2021/0073 20130101 |
Class at
Publication: |
165/173 ;
165/110 |
International
Class: |
F28F 9/02 20060101
F28F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2003 |
DE |
103 15 371.3 |
Claims
1. A heat exchanger having at least a two-part header (2), which
comprises a tube plate (4) and a cover (5) and includes at least
two longitudinal passages (8, 9) which are substantially circular
in cross section, and having flat tubes (3), the flat tubes (3)
having tube ends (3a), and the tube plate (4) having openings (11)
for receiving the tube ends (3a), and the tube plate (4), cover (5)
and flat tubes (3) being brazed together, characterized in that the
tube plate (4) and the cover (5) are each produced from a flat
metal sheet, such as in particular by stamping, and have at least
one central longitudinal partition region (12, 13) with transverse
passages (10) arranged in the region of the flat tubes (3) and
contact surfaces (14, 15) arranged between the flat tubes (3), and
are brazed in the region of the contact surfaces (14, 15).
2. The heat exchanger as claimed in claim 1, characterized in that
the contact surfaces (14, 15) of the tube plate (4) and of the
cover (5) are formed as elevations on the inner side, with
corresponding recesses (18, 17) on the outer side.
3. The heat exchanger as claimed in claim 1, characterized in that
the transverse passages (10) are in the form of stamped recesses on
the inner side, with corresponding elevations (19, 20) on the outer
side.
4. The heat exchanger as claimed in claim 2, characterized in that
the tube plate (4) and the cover (5) have an approximately constant
wall thickness s in the region of the elevations and recesses.
5. The heat exchanger as claimed in claim 1, characterized in that
the header (2) has a centrally arranged parting plane (6), and in
that elevations and recesses are arranged symmetrically with
respect to the parting plane (6).
6. The heat exchanger as claimed in claim 1, characterized in that
the header (2) has a centrally arranged parting plane (6), and in
that elevations and recesses are arranged asymmetrically with
respect to the parting plane (6).
7. The heat exchanger as claimed in claim 2, characterized in that
the elevations and recesses form a trapezoidal profile when seen in
longitudinal section.
8. The heat exchanger as claimed in claim 7, characterized in that
the contact surfaces (14, 15) are formed as approximately
rectangular surfaces (14, 15).
9. The heat exchanger as claimed in claim 1, characterized in that
the cover (5) and the tube plate (4) each have an edge region in
which they are brazed.
10. The heat exchanger as claimed in claim 9, characterized in that
the edge region of the tube plate (4) includes edge strips (7)
and/or tabs.
11. The heat exchanger as claimed in claim 10, characterized in
that the edge region of the tube plate engages over the edge region
of the cover (5).
12. The heat exchanger as claimed in claim 9, characterized in that
the cover has edge strips and/or tabs.
13. The heat exchanger as claimed in claim 12, characterized in
that the edge region of the cover engages over the edge region of
the tube plate.
14. The heat exchanger as claimed in claim 1, characterized in that
the header (22) has at least three longitudinal passages (24, 25,
26) and at least two longitudinal partitions (30, 31) with
elevations and recesses (32, 33).
15. The heat exchanger as claimed in one of the preceding claims
claim 1, characterized in that at least two longitudinal passages
have different cross sections.
16. The heat exchanger as claimed in claim 1, characterized in that
at least two contact surfaces are of different sizes or have
different cross sections, in particular in terms of width and/or
length.
17. The heat exchanger as claimed in claim 1, characterized in that
the heat exchanger is designed or can be operated as a gas cooler
or a condenser.
Description
[0001] The invention relates to a heat exchanger, in particular in
accordance with the preamble of patent claim 1.
[0002] Heat exchangers for air-conditioning systems using R134a as
refrigerant comprise a heat exchanger network made up of flat tubes
and corrugation fins, as well as collection tubes which are
arranged on both sides of the network and are preferably circular
in cross section, as are known from DE-A 42 38 853 in the name of
the present Applicant. Designs of this type have a sufficient
strength to cope with the pressures which occur in a condenser.
However, with more recent refrigerants, such as CO.sub.2, the
pressures are considerably higher and the conventional designs of
heat exchangers are no longer able to cope with such pressures.
Therefore, in the extruded collection tube of increased wall
thickness disclosed by WO 98/51983, it has been proposed that a
collection tube comprise four flow passages of circular cross
section arranged next to one another. An extruded collection tube
of this type is expensive to produce, on account of the tooling
required. Another type of collection tube for high internal
pressures has been proposed in DE-A 199 06 289, in which the
collection tube is assembled from two or three extruded or pressed
parts and has two longitudinal passages which are circular in cross
section. If this known collection tube is composed of extruded
parts, the relatively high tooling costs are disadvantageous; if
the known collection tube is composed of pressed parts, the shape
appears to be incomplete, i.e. inadequately adapted to the expected
stresses caused by the high internal pressure.
[0003] A further design of the header of a conventional condenser
has been disclosed by U.S. Pat. No. 5,172,761. The condenser has
flat tubes which are received in slot-like openings in a
substantially planar but profiled tube plate. A substantially
planar but also profiled cover part is connected to the tube plate.
The tube plate and cover form individual chambers which are divided
by transverse walls and in which the refrigerant flows or is
diverted. Although the tube plate and cover are brazed to one
another in the region of the tubes by means of inwardly facing
stamped formations, this shape of a header does not appear suitable
for relatively high pressures, as occur in particular in a CO.sub.2
refrigerant circuit.
[0004] It is an object of the present invention to improve a heat
exchanger of the type described in the introduction in such a
manner, in terms of the design of the header, that it can be
produced easily and at low cost and is better able to withstand the
high demands in terms of internal pressure.
[0005] This object is achieved by the combination of features of
patent claim 1. The header is produced from two stamped or bent
sheet-metal plates, i.e. there is no material-removing machining
step. This leads to low production costs. Furthermore, the stamping
of the metal sheet produces cold work-hardening, which increases
the ability of the header to withstand internal pressure. The
stamping operation forms longitudinal partitions with contact
surfaces and transverse passages both at the cover and at the tube
plate, with the contact surfaces each being arranged between the
tubes or the openings in the tube plate. When joining cover and
tube plate, the contact surfaces bear flat against one another and
thereby form a large number of brazing surfaces in the region of
the longitudinal partition. Therefore, tube plate and cover are
brazed, on the one hand, in the edge region and, on the other hand,
in the region of the partition, where the brazed contact surfaces
form "tie rods", increasing the resistance to the internal pressure
which occurs within the header. This creates a pressure-resistant
and inexpensive header.
[0006] The end sides of the longitudinal passages may, for example,
be closed off by stoppers, covers or terminating walls and, if
appropriate, then brazed, or may be provided with refrigerant
connections. The end sides of the longitudinal passages can also be
closed off by suitable deformation of the cover and/or tube plate
by them being brazed together. The flat tube ends which project
into the tube plate or header are bridged in the region of the
longitudinal partition by the curved transverse passages, so that
the refrigerant can flow into or out of the flat tubes over the
entire cross-sectional region.
[0007] According to an advantageous refinement of the invention,
the contact surfaces on the inner side of the header are formed as
elevations and on the outer side of the header are formed as
recesses or stamped indentations, with the recesses or stamped
indentations and elevations or stamped projections corresponding to
one another in terms of their position. This production and
formation of the elevations on the inner side ensures a planar
bearing surface and therefore secure and strong brazing.
[0008] According to a further advantageous configuration of the
invention, the transverse passages, i.e. the connections from one
longitudinal chamber to others, are designed as recesses on the
inner side and accordingly as elevations on the outer side. The
formation of the transverse passages on the inner side ensures free
outlet cross sections of the flat tubes and good brazing of the
flat tube ends to the inner side, on account of the formation of a
meniscus.
[0009] In a further configuration of the invention, the wall
thickness is approximately constant in the region of the
longitudinal partitions of tube plate and cover, and the elevations
and recesses are preferably formed symmetrically with respect to a
central parting plane, with a trapezoidal contour as seen in
longitudinal section. This design results in a favorable fiber
profile for the sheet-metal material, good cold work-hardening,
i.e. a high toughness and strength of the header, in particular in
combination with the brazed, rectangular contact surfaces between
the flat tubes as tie rods.
[0010] According to an advantageous refinement of the invention,
the tube plate (or also the cover) has edge strips or tabs in the
edge region. The cover and tube plate are therefore fixed by means
of the strips or tabs before they are brazed together with the
entire heat exchanger.
[0011] According to a further advantageous configuration of the
invention, there are three or more longitudinal chambers having two
or more longitudinal partitions, with the longitudinal partitions
being formed analogously to the individual longitudinal partition
described above. This allows the header according to the invention
to be used even for relatively large depths of flat tube without
the longitudinal passages adopting an excessively large diameter.
This gives advantages in terms of installation space and the
strength of the header.
[0012] Further advantageous refinements are described in the
subclaims.
[0013] Exemplary embodiments of the invention are illustrated in
the drawing and described in more detail in the text which follows,
in which:
[0014] FIG. 1 shows a perspective partial view of a gas cooler,
[0015] FIG. 2 shows a side view of the gas cooler illustrated in
FIG. 1,
[0016] FIG. 3 shows a partial view of the gas cooler shown in FIG.
1 from the front,
[0017] FIG. 4 shows a section on line IV-IV in FIG. 3,
[0018] FIG. 5 shows an enlarged section as shown in FIG. 4, but
without the flat tube,
[0019] FIG. 6 shows a section on line VI-VI in FIG. 2,
[0020] FIG. 7 shows a cross section through the tube plate of the
header,
[0021] FIG. 7a shows a view from below onto the header shown in
FIG. 7,
[0022] FIG. 7b shows a view from above onto the header shown in
FIG. 7,
[0023] FIG. 8 shows a cross section through the cover of the
header,
[0024] FIG. 8a shows a view from below onto the cover shown in FIG.
8,
[0025] FIG. 8b shows a view from above onto the header shown in
FIG. 8,
[0026] FIG. 9 shows a further exemplary embodiment of the invention
with a header having three longitudinal passages, and
[0027] FIG. 10 shows a cross section through the header as shown in
FIG. 9, without flat tube,
[0028] FIG. 11 shows a cross section through the header with flat
tube, and
[0029] FIG. 12 shows a cross section through the header with
header.
[0030] FIG. 1 shows a heat exchanger which is designed as a gas
cooler 1 and has a header 2 and flat tubes 3 which open out into
the header and between which corrugation fins (not shown) may be
arranged. A gas cooler of this type is used in refrigerant circuits
for motor vehicle air-conditioning systems operated with CO.sub.2
as refrigerant, but can also be used in general as a
pressure-resistant heat exchanger.
[0031] FIG. 2 shows a side view of the gas cooler 1 with the header
2 which is composed of a tube plate 4 and a cover 5. The tube plate
4 and cover 5 are approximately W-shaped and formed and arranged
symmetrically with respect to a parting plane 6, with the tube
plate 4 having edge strips 7 which engage laterally around and fix
the cover 5. Tube plate 4 and cover 5 form two longitudinal
passages 8, 9, which are both substantially circular in cross
section. The flat tubes 3 are received by the tube plate 4 and
their flat tube ends 3a project into the longitudinal passages 8, 9
approximately as far as the parting plane 6. The tube plate 4 and
cover 5 are cut from a sheet-metal plate (not shown in more detail)
and are converted into the form illustrated by stamping or bending,
i.e. are produced without the need for a material-removing
machining process. After the individual parts, such as flat tubes
3, tube plate 4 and cover 5 have been joined, the entire gas cooler
1, which may also have another header (not shown), is brazed.
[0032] FIG. 3 shows a front view of an excerpt from the gas cooler
1, i.e. as seen in the direction of view onto the narrow sides of
the flat tubes 3 and the continuous strip 7 of the tube plate 4.
Instead of the continuous strip 7, it is also possible to provide
individual tabs (not shown), since these substantially only have a
fixing function for the subsequent brazing operation. As has
already been mentioned, corrugation fins (not shown), over which
ambient air flows in a direction perpendicular to the plane of the
drawing, may be arranged between the flat tubes 3.
[0033] FIG. 4 shows a section on line IV-IV in FIG. 3, i.e. a cross
section through the header 2 with tube plate 4 which receives a
flat tube 3 (not shown in section). A transverse passage 10, which
forms a through-connection, is arranged between the two
longitudinal passages 8, 9.
[0034] FIG. 5 shows an enlarged illustration of the header 2
without the flat tube 3, having a slot-like opening 11 in the tube
plate 4 for receiving the flat tubes 3. As has already been
mentioned, the header 2 has a parting plane 6, with respect to
which tube plate 4 and cover 5, with the exception of the edge
strips 7 and the receiving openings 11, are formed approximately
symmetrically, in particular in the region of a longitudinal
partition which separates the two longitudinal passages and is
formed from a longitudinal partition region 12 of the tube plate 4
and from a longitudinal partition region 13 of the cover 5, which
form contact surfaces 14, 15 bearing against one another. The
contact surfaces 14, 15 which bear against one another are in each
case arranged between the flat tubes 3 and therefore lie behind the
plane of the drawing, in which the transverse passage 10
and--symmetrically with respect thereto--a further transverse
passage 16 are located. The two transverse passages 10, 16
complement one another to form a common passage cross section.
[0035] FIG. 6 shows a section on line VI-VI in FIG. 2, i.e. in the
region of the longitudinal partition or the two longitudinal
partition regions 12, 13. The latter, in the region of the parting
plane 6, butt against one another by way of their contact surfaces
14, 15, which are each arranged between the flat tubes 3. The
contact surfaces 14, 15 in tube plate 4 and cover 5 are each
designed as elevations or stamped projections, opposite each of
which there is a recess 17 in the cover or a recess 18 in the tube
plate. The transverse passages 10 in the cover 5 are formed by
recesses on the inner side, opposite which are elevations 19 in the
cover; in a corresponding way, opposite the transverse passages 16
in the tube plate 4 are elevations 20 on the outer side of the tube
plate. The elevations and recesses in each case produce a
trapezoidally meandering profile with an approximately constant
wall thickness s for the longitudinal partition regions 12, 13 of
tube plate and cover. Since the elevations and recesses--as has
already been mentioned--are produced by stamping, the result here
is a favorable fiber profile and high cold work-hardening, which is
particularly advantageous for absorbing tensile forces in this
region.
[0036] FIG. 7 shows a cross section through the tube plate 4, FIG.
7a shows a view of the tube plate 4 from below and FIG. 7b shows a
view of the tube plate 4 from above. The contact surfaces 14, which
are approximately rectangular in form, can be seen between the
slot-like openings 11 in the tube plate on the inner side of the
tube plate 4 in FIG. 7b. The recesses 18 lie opposite these contact
surfaces 14 on the outer side of the tube plate 4 in FIG. 7a. The
elevations on the outer side of the tube plate are denoted by
20.
[0037] FIG. 8 shows the cover 5 in cross section, FIG. 8a shows a
view of the cover 5 from below and FIG. 8b shows a view of the
cover 5 from above, i.e. its inner side. The stamped depressions 17
can be seen as rectangular surfaces in FIG. 8a, with the contact
surfaces 15 located opposite them as elevations on the inner side
of the cover 5 (FIG. 8b). The transverse passages 10 extend between
the elevations 15.
[0038] The contact surfaces 14 (FIG. 7b) and the contact surfaces
15 (FIG. 8b) approximately correspond to one another in terms of
size and position, and after the tube plate 4 and cover 5 have been
joined bear against one another and are brazed together in this
region. For this purpose, the sheet-metal plates used as starting
material for tube plate 4 and cover 5 may be plated with brazing
solder on both sides. The base material for the sheet-metal plates
and also the flat tubes 3 and, if appropriate, the corrugation fins
is an aluminum alloy or various aluminum alloys.
[0039] FIG. 9 shows a further exemplary embodiment of the
invention, specifically a gas cooler 21, with a header 22 and a
series of flat tubes 23 which are received by the header 22 at the
end side.
[0040] FIG. 10 shows the header 22 in cross section without flat
tube 23. The header 22 has three longitudinal passages 24, 25, 26
which are formed by a tube plate 27 and a cover 28. A continuous
slot 29 having the dimensions of the ends of the flat tubes 23 has
been formed in the tube plate 27, preferably by stamping. The
longitudinal passages 24, 25, 26 are formed by two longitudinal
partitions 30, 31 which are formed similarly to the longitudinal
partition described above, comprising longitudinal partition
regions of tube plate and cover. Transverse passages 32 and 33 are
also provided by recesses. The illustration reveals that the header
according to the invention can be designed with any desired number
of longitudinal passages, with the contact surfaces according to
the invention for forming tie rods in each case being provided
between two adjacent longitudinal passages.
[0041] FIG. 11 shows a section through a collection tube of a gas
cooler 100 having the header 102, which is also referred to as a
collection tube. The header is of two-part configuration and is
composed of a tube plate 104 and a cover 105. The cover 105 is
fitted into the tube plate. This is carried out in such a way that
the side arms of the tube plate engage around the cover, so that
side faces of the cover bear against inner surfaces of the tube
plate. Tabs 135, which can be deformed prior to the brazing process
in order to secure the cover in the tube plate, are advantageously
arranged on the tube plate. Partitions 134 can be introduced, for
example pushed, into openings in the cover in order to divide the
collection tubes. These partitions can likewise be secured by means
of tabs. The partitions are advantageously approximately B-shaped
in form and bear against the contour of the tube plate. Tube plate
104 and cover 105 form at least two, optionally also 3, 4 or more,
longitudinal passages, which are both substantially circular or
oval in cross section. The flat tubes 103 are received by the tube
plate 104, and their flat tube ends project into the longitudinal
passages, approximately as far as a parting plane. Tube plate 104
and cover 105 are cut out of a sheet-metal plate (not shown) and
converted into the shape illustrated by stamping or bending, i.e.
produced without the need for a material-removing machining
process. However, the production process may also be carried out in
a different order, i.e. first of all the sheet-metal plate is
deformed, and then the tube plate or cover is punched out. After
the individual parts, such as flat tubes 103, tube plate 104 and
cover 105, have been joined, the entire gas cooler 1, which may
also include another header (not shown), can be brazed.
[0042] FIG. 12 shows a further exemplary embodiment of the
invention, in which the configuration of tube plate and cover are
similar to in FIG. 11, except that in FIG. 12 the tube plate and
cover have been swapped over, i.e. in FIG. 12 the side arms of the
cover engage around the outside of the tube plate, and the tabs are
formed on the arms of the cover. Another advantage in this case is
that the tabs can come to bear laterally against the tubes 103
and/or may be arranged between two tubes.
[0043] In both cases, i.e. FIG. 11 and FIG. 12, the tube plate and
cover have two approximately semicircular regions which are
connected by an approximately straight portion. Arms which are
oriented approximately perpendicular with respect to the central
region are provided on the parts, such as tube plate or cover,
which engage around the respective other part.
[0044] It is also possible for further components, such as flanges
or the like, to be connected to the tabs 135.
LIST Of Designations
[0045] 1, 100 Gas cooler [0046] 2, 102 Header [0047] 3, 103 Flat
tube [0048] 4, 104 Tube plate [0049] 5, 105 Cover [0050] 6 Parting
plane [0051] 7 Edge strip [0052] 8 Longitudinal passage [0053] 9
Longitudinal passage [0054] 10 Transverse passage [0055] 11 Opening
in the tube plate [0056] 12 Longitudinal partition region, tube
plate [0057] 13 Longitudinal partition region, cover [0058] 14
Contact surface, tube plate [0059] 15 Contact surface, cover [0060]
16 Transverse passage [0061] 17 Recess, cover [0062] 18 Recess,
tube plate [0063] 19 Elevation, cover [0064] 20 Elevation, tube
plate [0065] 21 Gas cooler [0066] 22 Header [0067] 23 Flat tube
[0068] 24 Longitudinal passage [0069] 25 Longitudinal passage
[0070] 26 Longitudinal passage [0071] 27 Tube plate [0072] 28 Cover
[0073] 29 Slot [0074] 30 Longitudinal partition [0075] 134
Longitudinal partition [0076] 135 Tab
* * * * *